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authorjohn stultz <johnstul@us.ibm.com>2007-05-21 14:31:52 +0200
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-21 09:56:57 -0700
commitd0aff6e6f4e54f79f9c89d147d371bad384454e9 (patch)
treec6ee8e8630600029d322569f20602dc586f4fbf5 /arch/x86_64/kernel
parentd8902bfcacde6001e1b11bb06137c3bae3ae52d0 (diff)
x86_64: vsyscall time() fix
The vsyscall time() function basically returns the second portion of xtime directly. This however means that there is about a ticks worth of time each second where time() will return a second value less then what gettimeofday() does. Additionally, this window where vtime() is behind vgettimeofday() grows when dynticks is enabled, so its probably good to get this in before dynticks lands. Big thanks to Sripathi for noticing this issue and creating a test case to work with! This patch changes the vtime() implemenation to call vgettimeofday(), much as syscall time() implementation calls gettimeofday(). 2.6.21 stable candidate too Signed-off-by: John Stultz <johnstul@us.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86_64/kernel')
-rw-r--r--arch/x86_64/kernel/vsyscall.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86_64/kernel/vsyscall.c b/arch/x86_64/kernel/vsyscall.c
index 51d4c6fa88c..57660d58d50 100644
--- a/arch/x86_64/kernel/vsyscall.c
+++ b/arch/x86_64/kernel/vsyscall.c
@@ -175,10 +175,13 @@ int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
* unlikely */
time_t __vsyscall(1) vtime(time_t *t)
{
+ struct timeval tv;
time_t result;
if (unlikely(!__vsyscall_gtod_data.sysctl_enabled))
return time_syscall(t);
- result = __vsyscall_gtod_data.wall_time_sec;
+
+ vgettimeofday(&tv, 0);
+ result = tv.tv_sec;
if (t)
*t = result;
return result;